Professional image of dentists in Hong Kong

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Filtering of false positive microRNA candidates by a clustering-based approach

B M C BioinformaticsBackground: MicroRNAs are small non-coding RNA gene products that play diversified roles from species to species. The explosive growth of microRNA researches in recent years proves the importance of microRNAs in the biological system and it is believed that microRNAs have valuable therapeutic potentials in human diseases. Continual efforts are therefore required to locate and verify the unknown microRNAs in various genomes. As many miRNAs are found to be arranged in clusters, meaning that they are in close proximity with their neighboring miRNAs, we are interested in utilizing the concept of microRNA clustering and applying it in microRNA computational prediction. Results: We first validate the microRNA clustering phenomenon in the human, mouse and rat genomes. There are 45.45%, 51.86% and 48.67% of the total miRNAs that are clustered in the three genomes, respectively. We then conduct sequence and secondary structure similarity analyses among clustered miRNAs, non-clustered miRNAs, neighboring sequences of clustered miRNAs and random sequences, and find that clustered miRNAs are structurally more similar to one another, and the RNAdistance score can be used to assess the structural similarity between two sequences. We therefore design a clustering-based approach which utilizes this observation to filter false positives from a list of candidates generated by a selected microRNA prediction program, and successfully raise the positive predictive value by a considerable amount ranging from 15.23% to 23.19% in the human, mouse and rat genomes, while keeping a reasonably high sensitivity. Conclusion: Our clustering-based approach is able to increase the effectiveness of currently available microRNA prediction program by raising the positive predictive value while maintaining a high sensitivity, and hence can serve as a filtering step. We believe that it is worthwhile to carry out further experiments and tests with our approach using data from other genomes and other prediction software tools. Better results may be achieved with fine-tuning of parameters. © 2008 Leung et al; licensee BioMed Central Ltd.published_or_final_versio

Irradiation or autoimmune disease induced hyposalivation: impact on oral health

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Saliva profile of irradiated cancer survivors and Sjogren's syndrome patients

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Oral perception/motor ability in edentulous patients with stroke and Parkinsonism

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Incidence of neurosensory deficits and recovery after lower third molar surgery: a prospective clinical study of 4338 cases

A prospective study of all lower third molar surgery performed in the outpatient extraction clinic of a teaching dental hospital was conducted from January 1998 through October 2005 to determine the incidence of subsequent neurosensory deficit due to inferior alveolar nerve (IAN) and lingual nerve (LN) injury, to examine possible contributing risk factors and to describe the pattern of recovery. 3595 patients were included (61% female, 39% male; age range, 14-82 years). Of the 4338 lower third molar extractions performed by various grades of operators, 0.35% developed IAN deficit and 0.69% developed LN deficit. Distoangular impaction was found to increase the risk of LN deficit significantly (p < 0.001). Depth of impaction was related to the risk of IAN deficit (p < 0.001). Undergraduates caused more LN deficits (p < 0.001). Sex, age, raising of a lingual flap, protection of LN with a retractor, removal of distolingual cortex, tooth sectioning and difficulty in tooth elevation were not significantly related to IAN or LN injury. Postoperative recovery from IAN and LN deficits was noted most significantly at 3 and 6 months, respectively. By the end of the follow-up period, 67% of IAN deficits and 72% of LN deficits had recovered completely. © 2009 International Association of Oral and Maxillofacial Surgeons.postprin

Effects of smoking on healing response to non-surgical periodontal therapy: A multilevel modelling analysis

Wan CP, Leung WK, Wong MCM, Wong RMS, Wan P, Lo ECM, Corbet EF. Effects of smoking on healing response to non-surgical periodontal therapy: a multilevel modelling analysis. J Clin Periodontol 2009; 36: 229-239. doi: 10.1111/j.1600-051X.2008.01371.x. Abstract Aim: To investigate the factors predicting non-surgical periodontal treatment responses using multilevel multiple regression. Material and Methods: Forty men (mean 45.6 years) were recruited; 20 were smokers. A 12-month reduction in probing pocket depth (PPD) and gain in probing attachment level (PAL) of 5814 sites were analysed, with 594 being initially diseased sites (initial PPD≥5 mm). Results: Variance Component models showed that site-level variations contributed about 70-90% of the total variance. About a 10% reduction of the total variations of PPD reduction in initially diseased sites was achieved with the inclusion of the 10 predictors in the multilevel multiple regression. Multilevel multiple regression showed that three predictors, subject level: non-smokers; tooth-level: anterior teeth; and site level: sites without plaque at baseline, were significantly associated with a greater reduction in PPD in initially diseased sites over the 12-month study period (p<0.05). No consistent predictor was found for PAL gain. Conclusion: Multilevel analysis was applied on periodontal treatment response data. Smokers showed less favourable PPD reduction at deep sites after non-surgical periodontal therapy. © 2009 John Wiley & Sons A/S.postprin

Oral health status of Sjogren's syndrome patients in Hong Kong

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Health-related quality of life in Sjogren's syndrome

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Impact of Sjögren's syndrome on oral health-related quality of life in southern Chinese

The effect of oral symptoms of Sjögren's syndrome (SS) on health-related quality of life is presently uncertain. This study aimed to investigate oral health-related quality of life (OHRQOL) among southern Chinese people with SS. Twenty-six primary SS cases, 25 secondary cases and 29 matched controls took part in this cross-sectional study. Each participant completed a SF-36 questionnaire, the Oral Health Impact Profile and a dry mouth measure, assisted by a trained interviewer. Data on socio-demographic variables were also collected. The dry mouth measure revealed that people with primary and secondary SS had significant problems associated with subjective symptoms of dry mouth generally, and dry mouth when eating and speaking (P < 0.01). Sticky saliva and coughing were also problems in some primary SS cases. OHIP summary and sub-scale scores did not reveal differences in negative impacts between groups. Mean SF-36 sub-scale scores were significantly different between groups (P < 0.05). In physical function, role-physical and general health domains, primary and secondary SS sufferers had lower scores indicating poorer health. Oral symptoms of SS, notably xerostomia, had a negative effect on OHRQOL. Health-related quality of life in general was also impaired in SS sufferers. The OHIP did not appear to discriminate oral problems of concern to SS sufferers.postprin